Fuji Electric PXR4-TAY1-4V0A1 Temperature Controller, Curren

It's the piece that reads a thermocouple or RTD input and drives an output — typically a relay or solid-state switch — to hold a setpoint on a heater, oven, or process bath. In a panel, it mounts into a standard DIN cutout and connects to the sensor on one side and the power-switching element on the other. Lifecycle stage is listed as current.